The engagement hypothesis suggests that age-related declines in cognition may to some extent be mitigated by a lifestyle marked by social and intellectual engagement. According to this view, contexts that require choice and decision-making in the face of ill-defined problems promote mental flexibility. Assuming that the environment provides rewards for effective solutions and creates opportunities for self-directed activity, complex environments continue to promote the allocation of resources toward intellectual activity, thereby expanding the repertoire of intellectual skills available to solve new problems, and to augment cognition and well-being in a variety of ways. Evidence for this idea, however, is primarily based on correlational data, which is subject to other interpretations, making it unclear whether engagement enhances cognitive function - or whether more intellectually capable individuals are prone to engagement. Training studies (e.g., the ACTIVE trials, Ball et al., 2002), in which cognitive and intellectual abilities are selectively trained, have been found to produce little or no transfer to other abilities; furthermore, studies of expertise (e.g., Morrow et al., 1994) show very narrow effects of experience. The current project is a translational research program, which attempts to bridge these two literatures by experimentally manipulating the substantive complexity of lifestyle for a six-month period. Participants will be randomly assigned to a program of engagement in which subjects participate in collaborative problem solving and literacy activities (our operationalization of a substantively complex environment), to a crossword puzzle / brainteaser control, or to a wait-list control. The engagement experience is modeled on an existing program, Odyssey of the Mind, developed for children and young adults (through college-aged); this existing social structure offers potential for scaling up so as to afford opportunities for intellectual and social stimulation for elders. A pretest and posttest battery of cognitive (e.g., speed, executive functions, fluency), dispositional measures indicating, self-regulatory effectiveness (e.g., mindfulness, self-efficacy), and activity (e.g., Hultsch Activity Scale, Day Reconstruction Method) will allow us to test the hypothesis that this form of engagement can augment cognitive function and self-regulatory capacity, in a context which may find ready translation into practice. [unreadable] [unreadable] [unreadable]